Pain is one of the most common medical conditions requiring interventions with 25 million people in the US suffering from chronic pain alone and chronic pain management costing $65 Billion annually. Pain can be the result of a large number of medical conditions and can range in severity from mild to intractable. Despite a broad range of therapeutic and non-therapeutic interventions, there is still a large unmet need for effective and safe pain medications.
Lactoferrin is a single-chain metal binding glycoprotein. Many cell types, such as monocytes, macrophages, lymphocytes, and brush-border cells in the intestine, are known to have lactoferrin receptors. Lactoferrin is found mainly in external secretions of mucosal epithelia such as breast milk, saliva, tears, bile, and pancreatic fluid and has a wide array of functions related to host primary defense mechanisms. For example, lactoferrin has been reported to activate natural killer (NK) cells, induce colony-stimulating activity, activate polymorphonuclear neutrophils (PMN), regulate granulopoeisis, enhance antibody-dependent cell cytotoxicity, stimulate lymphokine-activated killer (LAK) cell activity, and potentiate macrophage toxicity.
Recombinant human lactoferrin has previously been described as being purified after expression in a variety of prokaryotic and eukaryotic organisms including aspergillus (U.S. Pat. No. 6,080,559), cattle (U.S. Pat. No. 5,919,913), rice, corn, Sacharomcyes (U.S. Pat. No. 6,228,614) and Pichia pastoris (U.S. Pat. No. 6,455,687, U.S. Pat. No. 6,277,817, U.S. Pat. No. 6,066,469). Also described are expression systems for the expression of full-length human lactoferrins (e.g., U.S. Pat. No. 6,100,054). In all cases, part of the teaching is expression of the full-length cDNA and purification of the intact protein whose N-terminal amino acid is, after processing of the leader peptide, the amino acid glycine. Nuijens et al. (U.S. Pat. No. 6,333,311) separately describe variants of human lactoferrin but their focus is limited to deletion or substitution of arginine residues found in the N-terminal domain of lactoferrin.
The present invention is the first to use a lactoferrin composition as a means of reducing or eliminating pain associated with a broad range of medical conditions.